Sedimentary / Mineral
Agate Nodule / Weathered Chert
SiO2 (Silicon Dioxide - Microcrystalline Quartz)
Hardness: 6.5-7, Color: Brown, tan, yellowish, Luster: Waxy to dull (on weathered exterior), Crystal structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
- Hardness
- 6
Identified More sedimentary / mineral →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7, Color: Brown, tan, yellowish, Luster: Waxy to dull (on weathered exterior), Crystal structure: Cryptocrystalline, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed through the deposition of silica from groundwater in cavities of igneous or sedimentary rocks. The rough exterior is due to weathering and tumbling in natural environments.
Uses & applications
Often collected by rockhounds for tumbling or lapidary work. It has little industrial value but is a fun find for collectors.
Geological facts
Many of these weathered nodules appear unremarkable on the outside but can contain beautiful banding or quartz pockets inside when cut or polished.
Field identification & locations
Identify by its hardness (will scratch glass), nodular shape, and waxy luster if broken. Commonly found in riverbeds, glacial till, and desert environments.
More like this
Other sedimentary / mineral specimens
Celestite (Celestine) Geode
Strontium Sulfate (SrSO4)
mineral
Assorted Tumbled Gemstones
Mixed oxides and silicates (including Quartz, Chalcedony, and Feldspar variants)
mineral
Blue Apatite
Calcium Phosphate (Ca5(PO4)3(F,Cl,OH))
mineral
Celestite (Celestine)
Strontium sulfate (SrSO4)
mineral
Celestite (Celestine)
Strontium sulfate (SrSO4)
mineral
Blue Caribbean Calite
Calcium Carbonate (CaCO3) with trace Aragonite
mineral